Only set bounds when annotation is visible.

[jascase901]

the set bounds function is actually kinda cpu intensive. I noticed that when there are thousands of bounding boxes in your video sequence, it can add seconds to moving bounding boxes, creating bounding boxes, and switching to another image frame. reduces the ammount of times set bounds is called by only calling the function when annotations are set to appear visibile.

This is the time it used to take to draw annotations for a video with a few hundred bounding boxes

this is the time it takes to draw annotations after.